CORPUS CHRISTI, Tex. — Hurricane Harvey flattened buildings in the small city of Rockport and slowed to a crawl Saturday, gradually losing hurricane status but remaining strong and potentially deadly as it inundates communities with extraordinary rainfall and threatens catastrophic flooding.

Rockport Mayor C.J. Wax confirmed one fatality, and officials in Texas expect to find further victims as search and rescue operations proceed along the battered central Texas coast.

“We have not been able to completely assess damage with current winds at 90+,” Wax said earlier in the day in an email to The Washington Post. “Widespread devastation unknown loss of life.”

On social media, residents and others who rode out the storm in Rockport reported that numerous buildings had been destroyed. Officials said it was too early to measure the scale of the destruction.

Images of downed trees, collapsed buildings and darkened streets began trickling in early in the day, after the storm roared ashore at 10 p.m. Central time Friday with 130 mph winds — the first Category 4 storm to hit the United States since Charley in 2004.

More than 200,000 people across the state were without power early Saturday, and wastewater and drinking-water treatment plants here were offline.

By late morning Saturday, Harvey had lost some of its punch but still had hurricane-force winds of 80 mph, having drifted to about 25 miles west of the inland city of Victoria. Then, shortly after noon, it was officially downgraded to a tropical storm, with sustained winds of 70 mph, but the bigger picture remains perilous.

Harvey’s storm track slowed to just 2 mph as it crept north, and in coming days it backtrack, meander to the east and possibly veer back out over the hot Gulf waters, allowing it to restrengthen to some extent. All the while it will dump dangerous quantities of rain.

The National Weather Service said some locations in Southeast Texas had already reported 16 inches of rain by 5 a.m. Central time and predicted total rain accumulations of 15 to 30 inches in many areas, with as much as 40 inches in isolated areas.

Most ominously, the area around Rockport could see up to 60 inches of rain through midweek.

“Please take the flooding threat seriously,” the National Weather Service tweeted. “Remember, this is a multiday event … marathon not a sprint …”

Gov. Greg Abbott (R) said he had declared 50 counties a disaster area. He said he had no information on confirmed fatalities. With the storm now ashore, he said, “our primary concern remains dramatic flooding.” He urged citizens to follow the familiar advice: “Turn around, don’t drown.”

The governor spoke to reporters two levels below ground in a bunker-like room at the State Operations Center in Austin. He spent much of the brief news conference praising the resilience of evacuees he’d met the day before in San Antonio, saying they were happy to be alive but worried about their homes and possessions in coastal communities.

Rivers are rising. The Tres Palacios River has already risen more than 20 feet near Midfield, Texas, according to the U.S. Geological Survey. The San Bernard River near the town of Sweeny is expected to rise more than 10 feet above its 1998 record flood stage. The Brazos River is expected to break a flood record set just last year, and officials have ordered mandatory evacuations in low-lying areas of Fort Bend County.

Among the cities at risk of major flooding is Houston, the nation’s fourth largest with a population in excess of 2 million. Early Saturday morning, the city was buffeted by waves of torrential rain and lightning followed by periods of calm.

In the southwest part of the city, Brays Bayou was swelling with fast-flowing, debris-filled brown water, and a tornado touched down in a suburban neighborhood.

Montry Ray was staying up late to ride out the storm with his wife and two children when the roaring sound of the tornado sent them running for cover in a bathroom. Just as they bolted from the master bedroom, the storm exploded through its wall, embedding bricks in the drywall across the room. The storm ripped open the roof.

“You know how they say you hear the train noise?” said 12-year-old Caden Hill, who lives down the street. “I heard it.”

He, along with about 50 neighbors, turned out Saturday morning to help clean up. Volunteers chopped fallen trees, hauled away crumpled fences and gathered debris while roofers patched the homes.

In Corpus Christi, the storm ripped shingles and satellite dishes off roofs, but the city did not appear to have suffered major destruction, Mayor Joe McComb said. The power outage disrupted the city’s wastewater treatment plant, and officials are asking residents to boil drinking water until further notice.

“The storm surge never happened, but the winds came in a whole lot higher than anyone predicted,” McComb said. “Some areas also got hit with pretty hard rain, but I was impressed with how little rain we had at my house.”

The 20-story Holiday Inn Marina hotel, where many relief workers and journalists rode out the storm, reported that it was running low on food. A note in the lobby and in elevators asked guests to use their own “emergency” food and water supplies before purchasing the hotel’s dwindling supplies. The hotel is a major staging area for Red Cross officials, who flew into the city ahead of the storm.

Weather officials took to social media and the airwaves Saturday in an effort to persuade people not to be lulled by a false sense of security by the relatively muted impact so far in places away from the Rockport area.

In Galveston, a city that lived through the last big Texas hurricane — Ike in 2008 — residents seemed unconcerned.

“We thought it was going to be much worse,” said Latoya Fulton, 33, who was eating breakfast with her husband and four children at Waffle House. The Fultons, who live in Galveston, spent Friday night in a hotel in Conroe, north of Houston, as a precaution. But they returned Saturday morning to their undamaged house when news reports made it clear that Galveston had been largely spared from the hurricane’s winds.

A few tables over at the packed restaurant — one of the few businesses open in the area — Galveston residents Dottie and Kevin Bowden ate breakfast with their 16-year-old granddaughter, Savannah Stewart.

“This ain’t nothing,” Kevin Bowden said.

All the houses in their neighborhood are built on stilts, so they weren’t worried about flooding, and local officials did not issue a mandatory evacuation order. Everyone in the neighborhood stayed to ride out the storm.

“We’re not crazy,” said Dottie, 63, who runs a business cleaning rental properties. “If they told us to leave, we would have.”

Rain was still slashing down in intermittent waves, and Galveston authorities still had flash-flood warnings in place. The forecast was for potentially severe rain to continue for days.

Kevin Bowden said the biggest problem so far was that “we’re running low on Corona.”

President Trump said in a series of tweets Saturday morning that he is closely monitoring the situation from Camp David and that federal officials have been on the ground since before the storm hit. He urged residents to “be safe” and pledged a thorough federal response. “We are leaving nothing to chance,” he wrote. “City, State and Federal Govs. working great together!”

Forecasters and government officials scrambled to deal with a storm that caught them off guard this week after initially being a mere tropical depression in the western Gulf of Mexico. By Friday, they were warning of catastrophic flooding, ferocious winds and a storm surge that could reach 12 feet.

Soon after the outer bands of Harvey reached the South Texas coast Friday afternoon, Gov. Greg Abbott (R) urged citizens to evacuate low-lying and coastal areas immediately. Trump said Friday night that he has signed a disaster proclamation in Texas after Abbott sent him a written request saying that “Texas is about to experience one of the worst natural disasters in the history of the state.”